The present invention relates to an electric inertia-actuated circuit breaker.
It concerns particularly a circuit breaker employed in a motor vehicle for breaking at least one electric circuit in the event of impact and/or overturning of the vehicle.
Documents FR-A-No. 2 151 585 and FR-A-No. 2 191 241 disclose and illustrate an inertia-actuated circuit breaker of the type comprising a piston to which is fixed an electrically conductive element and which is axially slidable inside a case between a position of rest in which the conductive element bears against two contact studs of an electric circuit which it interconnects, and a circuit-breaking position in which the electric circuit is broken, and a ball which, in the position of rest, is maintained resiliently gripped by a calibration spring acting on the piston, between a fixed concave seat of the case and a concave seat of the piston, the ball being maintained in position subtantially in the centre of a chamber of the case into which it is capable of escaping radially to permit the piston to occupy the circuit-breaking position thereof.
According to these documents, the circuit breaker is arranged to be disposed inside the motor vehicle so that the general axis of the case is vertical and the ball, in the event of collision, leaves its two concave seats under the effect of the lateral acceleration it undergoes.
This type of circuit breaker has several drawbacks. In the event of overturning of the vehicle, the circuit breaker is ineffective since the piston is unable to slide axially relative to the case in opposition to the resiliently yieldable force exerted by the calibration spring, the conductive element bearing against the two fixed contact studs of the electric circuit. Furthermore, when the various component parts of the circuit breaker are assembled, it is not possible to guarantee that the conductive element is, in its position of rest, in bearing relation to the two contact studs, in particular in the case where the resiliently yieldable force exerted by the calibration spring on the piston is excessive.